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This is a discussion on fuel question within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; i am looking into getting a new 2005 wrx and i was wondering if the car requires octane 93 fuel? ...

  1. #1
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    fuel question

    i am looking into getting a new 2005 wrx and i was wondering if the car requires octane 93 fuel? would it be ok if i were to put regular or maybe even the middle one octane 89?, would it hurt the engine if i didn't put octane 93 all the time?
    thanks

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    Registered User cyrilgrey's Avatar
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    This car requires a minimum of 91 octane to perform as advertised, otherwise known as "premium" fuel.

    If you fill the car with 87 the computer will sense a change in the way the engine runs and will make alterations resulting in a large loss of power. The car will run, no damage will occur, it will not perform the way it was intended to.

    If you are worried about the expense of premium fuel do not buy a WRX or a similar performance car.



    Mid range octane fuel is a marketing gimmick to make money off uninformed consumers. I cannot think of a single car rated for 89 octane. Either 87 or 91/93 are recommended. Unless you are experiencing slight pinging in a built motorcycle engine, or a car intended for 87 suffering the same, 89 is a waste of money.
    Last edited by cyrilgrey; 08-21-2005 at 05:45 PM.

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    Banned 05WRX0704's Avatar
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    any FI car will require 91+ octane. for example, when i moved to california with my old after market turbod car, i had to turn my boost down to 6.5psi because they only have 91 octane around here.

    the sti requires 93 (the manual says i believe).

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    Quote Originally Posted by cyrilgrey
    This car requires a minimum of 91 octane to perform as advertised, otherwise known as "premium" fuel.

    If you fill the car with 87 the computer will sense a change in the way the engine runs and will make alterations resulting in a large loss of power. The car will run, no damage will occur, it will not perform the way it was intended to.

    If you are worried about the expense of premium fuel do not buy a WRX or a similar performance car.



    Mid range octane fuel is a marketing gimmick to make money off uninformed consumers. I cannot think of a single car rated for 89 octane. Either 87 or 91/93 are recommended. Unless you are experiencing slight pinging in a built motorcycle engine, or a car intended for 87 suffering the same, 89 is a waste of money.

    Technically damage can occur. In order for the ECU to react to pinging, pinging must first occur. That and once you put regular in you'd probably need to reset the ECU to advance the timing all the way back to 16.

    Quote Originally Posted by lilneel12
    i am looking into getting a new 2005 wrx and i was wondering if the car requires octane 93 fuel? would it be ok if i were to put regular or maybe even the middle one octane 89?, would it hurt the engine if i didn't put octane 93 all the time?
    thanks
    It is a HORRIBLE, HORRIBLE, HORRIBLE idea, not to mention a COMPLETE waste of money, to put anything other than 93 into a WRX. Someone on NASIOC (and this is not verified) said they saw someone ran a dyno and saw a 40 WHP loss when going from 93 to 87.



    The difference between 87 and 93 has remained a fairly constant 20-25 cents per gallon for the last forever and a half. At 12 gallons per fill, that is (on the high side) 3 dollars per fill. At even 8 fills per month, or 2 per week (24 gallons @ 20 mpg = 480 miles per week = 25,000 miles a year), that's $24 per month. At 12 months, that's $288 a year. If your financial well-being is dependant upon a $288 yearly dynamic, you've got bigger issues.

    Note the above used worst case scenario variables.

    Putting 87 even in one time (emergency) is bad. That'll set the ECU back quite a bit in the firing sequence.

    If you put it in for 500 miles, you may as well buy a 2.5i or RS.
    Last edited by TacticalNuke; 08-21-2005 at 06:21 PM.

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    Banned 05WRX0704's Avatar
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    some of us cant get 93.

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    Registered User drummerboy's Avatar
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    Originally posted by TacticalNuke
    It is a HORRIBLE, HORRIBLE, HORRIBLE idea, not to mention a COMPLETE waste of money, to put anything other than 93 into a WRX.
    putting 91 octane isn't bad. the spec for wrx is 91 anyway. i think only sunoco offers anything greater that 91 (94)... but they're not at every corner over here.. but i do agree that 87 is definitely not a good thing.
    Last edited by drummerboy; 08-21-2005 at 07:12 PM.
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    Quote Originally Posted by 05WRX0704
    some of us cant get 93.
    I pretty much meant 91/93.

    BP, Sonoco and Shell offer 93/94.
    Last edited by TacticalNuke; 08-21-2005 at 07:47 PM.

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    Registered User cyrilgrey's Avatar
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    Some ping events will not impact the engine overall. The ECU is designed to adapt before damage actually occurs. It takes a while to cause any.

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    Quote Originally Posted by cyrilgrey
    Some ping events will not impact the engine overall. The ECU is designed to adapt before damage actually occurs. It takes a while to cause any.
    Learn something new every day.

    Either way, WRX - 40 HP = might as well get a 2.5 RS or 2.5i.

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    wow, i didn't realize it would gas would effect it that much, thanks for all of the info guys

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    Quote Originally Posted by lilneel12
    wow, i didn't realize it would gas would effect it that much, thanks for all of the info guys
    We're here to help and harass.

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